Dmitry’s mouth formed a big O shape, appropriately followed with a long “Ooooh.” That explained why he didn’t recognize the language. He was getting pretty good at English (which was to be expected after spending months at an American school) but he was still in a stage where he didn’t know enough to tell whether any unfamiliar words were real English or just casual slang.
Honestly, even in his native languages he didn’t often come across slang, as it wasn’t proper in the circles of his social class and not the sort of thing his parents tolerated even in the privacy of their home. There was a level of freedom he was permitted at home, and some boundaries he knew he could bend, but formal speech was always expected - whether out of deference to his seniors, setting a good example for his little sisters, or displaying authority with their staff. The only opportunity he had to learn slang was when he walked around the city, and even then, it was difficult with his guard Alyona following him like an unwelcoming shadow.
See, here was a great example why Tycho was both fun and helpful to work with! He gave a very clear explanation of what the words meant, but also he was smiling and seemed to recognize that they were funny words. And also saying even more strange words - what was basket ball? He knew basket, and he knew ball, duh, so it sounded like it meant putting a basket over a ball, but that sounded dumb. Why would someone be popular for doing that? Muggles were weird. Although, if Kobe was about accuracy, that suggested it took skill to put the basket on the ball. Maybe it was a very small ball they had to catch?
Anyways. “Kobe,” Dmitry echoed, rolling the word around in his mouth. Curiously, he drew his black walnut wand and pointed it at Tycho’s quill. “Kobe!” Nothing happened. Maybe he was saying it wrong. “Umm, yeety? Yeet.” The quill twitched a little, though it might have just been his imagination. Both disappointed and a little distracted, Dmitry asked, “Is it normal in English to have a person’s name as a slang word? That is confusing. What if you were talking to Kobe?”